JPH0577951A - Paper feeder - Google Patents

Abstract

PURPOSE:To optimize an amount of feeding back a transfer sheet by separating the first feed means from the sheet of a paper feed cassette when the first feed means and the second feed means in contact with a double feed preventing means are reversed. CONSTITUTION:A transfer sheet 2 fed from a paper feed mechanism 4 is conveyed to pass through a paper feed conveying path 34, on the halfway of which timing rollers 33 are provided, and to a transcription part where a sensitive body 10 is opposed to a transcription electrostatic charger 12. In the timing rollers 33, the transfer sheet 2 is fed in a stop condition to correct an oblique feed of the transfer sheet 2 by straightening its point end. Timing of feeding the transfer sheet 2 to the transcription part is adjusted in accordance with the timing of starting conveyance. The transfer sheet 2 of transcribing a toner image is separated from the sensitive body 10 and guided to a fixing device 15 by a conveyer 14. In the fixing device 15, by applying heat and pressure by a heating roller 16 and a pressure roller 17, the transfer sheet 2, completing copying by melting and fixing a toner on the transfer sheet 2, is discharged to the outside of a machine by a paper discharger device 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device used in a copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, in a copying machine or the like, a large number of transfer sheets are stored in a paper feeding cassette, the paper feeding cassette is inserted into the main body of the copying machine, and a feeding device of the main body of the copying machine stores the transfer Continuous transfer is possible by sending out the transfer sheets one by one. In recent years, in order to reduce the installation space of the copying machine or to improve the operability, a method of inserting the paper feed cassette from the front of the copying machine main body (hereinafter referred to as a front loading method) has been widely adopted.

The feeding device is composed of a feeding roller and a multi-feed preventing means such as a separating pad in order to feed the transfer sheets in the feeding cassette one by one. By the feeding, the transfer sheet to be fed next is caught in the double feeding preventing portion. In the front loading method, the direction in which the transfer sheet is sent out is orthogonal to the direction in which the paper cassette is inserted into the main body of the copying machine, so if you try to pull out the paper cassette when replenishing the transfer sheet, etc. When the leading edge of the transfer sheet is pulled out, the sheet cassette is pulled out, and the transfer sheet may be wrinkled or damaged.

As a means for solving this, Japanese Patent Application No. 2-1
No. 05575, a means for temporarily reversing the feeding means is provided, and the reversing means is operated for a predetermined time after the final feeding is completed to forcibly return the transfer sheet into the paper feeding cassette. There is.

[0005]

However, in the conventional method, if the reversing means is operated for too long, the transfer sheet is returned too much and the transfer sheet is wrinkled in the paper feeding cassette, or the transfer sheet is fed. There was a case where the paper came out of the roller and a paper jam occurred during the next paper feeding operation. Also, not only one type of paper cassette,
For example, there are a sheet feeding cassette for 250 sheets, a sheet feeding cassette for 500 sheets, and the like, and the feeding mechanism is often different due to the difference in the number of transfer sheets stacked. In particular, in a paper feeding device in which a paper feeding cassette and a feeding mechanism are paired to form a paper feeding module, and various kinds of paper feeding modules can be arbitrarily combined, the optimum return amount of the transfer sheet is set for each paper feeding module. However, it was difficult to realize the optimum return amount for all the paper feed modules by the conventional method.

The present invention provides a paper feeding device capable of preventing wrinkles and paper jams due to excessive return of a transfer sheet in a paper feeding cassette even in the case of an arbitrary combination of various paper feeding modules. is there.

[0007]

In order to achieve this object, a sheet feeding device of the present invention comprises a first sheet feeding means for feeding a sheet in a detachable sheet feeding cassette to which the sheet is pressed. The second feeding means is provided on the downstream side of the first feeding means, and the double feeding preventing means that comes into pressure contact with the feeding surface of the second feeding means and the first and second feeding means are temporarily provided. In the sheet feeding device having the means for reversing the sheet, the first sheet feeding means is separated from the sheet when the first and second sheet feeding means are reversed. Further, according to the present invention, a sheet feeding means for pressing a sheet in a detachable sheet feeding cassette to feed the sheet, a double feeding preventing means for pressing a sheet on a sheet feeding surface of the sheet feeding means, and a sheet feeding means are temporarily provided. In a paper feeding device provided with a means for reversing, when the reversing means is operated to reverse the feeding means, a delay mechanism is provided in the feeding means.

[0008]

According to the above-mentioned structure of the present invention, the second paper feed roller in contact with the double feed prevention means is rotated in the reverse direction so that the first paper feed roller located on the upstream side in the paper feed direction is transferred to the stacked transfer sheets. The transfer sheet can be separated from the surface, and the transfer sheet caught in the double-feeding preventing portion can be fed back into the paper feeding cassette without being obstructed by the first paper feeding roller. Further, according to the present invention, even when various kinds of paper feed modules are combined, the transfer sheet return amount can be set to an optimum value, and wrinkles and paper jams in the paper feed cassette can be prevented. You can

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the main part of a copying machine having a paper feeding device of the present invention. This copier has an exposure optical system 1
And an image forming mechanism 3 that forms an image by exposure by the exposure optical system 1 and transfers it to the transfer sheet 2, and a paper feed mechanism 4 that feeds the transfer sheet 2 to the image forming mechanism 3.

The exposure optical system 1 is composed of an exposure lamp 5, a mirror 6, a lens 7, etc., exposes and scans a document placed on a document table 8, and a photoconductor 10 charged with a projected image of the document by a charger 9. It forms an image on the top and forms a latent image.

The image forming mechanism 3 includes a photoconductor 10 and a charger 9, a developing device 11, a transfer charger 12, a cleaning device 13 and the like arranged around the photoconductor 10, and a latent image on the photoconductor 10 is formed. Is developed with toner in the developing device 11 to form a visible image, and the process proceeds to the transfer step. In the transfer step, the transfer sheet 2 fed by the paper feed mechanism 4 described later in detail on the visible image on the photoconductor is superposed on the visible image on the photoconductor 10, and the transfer charger 12 is applied from the back side thereof. By applying an electric charge having a polarity opposite to that of the toner, the toner particles forming a visible image move from the surface of the photoconductor 10 to the transfer sheet 2, and transfer is performed. The toner particles remaining after the transfer on the photoconductor 10 after the transfer process are
It is removed by the cleaning device 13.

The transfer sheet 2 on which the toner image is transferred
Is separated from the photoconductor 10, conveyed by the conveying device 14, and guided to the fixing device 15. In the fixing device 15, the toner on the transfer sheet 2 is melted and fixed by being heated and pressed by the heating roller 16 and the pressure roller 17, and copying is completed. The transfer sheet that has completed copying is ejected from the sheet ejection device 18
Is discharged outside the machine.

The paper feed mechanism 4 has three paper feed modules 19 to 21 for accommodating the transfer sheets 2 of different sizes and selectively feeding them. In this embodiment, the paper feed modules 19 and 20 are of a 250-sheet storage type, and the paper feed module 21 is of a 500-sheet storage type.

The 250-sheet storage type paper feed modules 19 and 20 each have a pickup roller 27 for feeding the transfer sheets 2 in the paper feed cassettes 22 to 23, and a separating pad 25 for separating the fed transfer sheets 2 one by one. have. Bottom plates 30 and 31 of the paper feed cassettes 22 and 23
Is pushed up by a push-up lever (not shown) that is biased by a spring force, and the uppermost surface of the transfer sheet 2 is pressed against the pickup roller 27.

The paper feed module 21 for storing 500 sheets is
A first sheet feeding roller 28 for feeding the transfer sheets 2 in the sheet feeding cassette 24, and a second sheet feeding roller 28 for feeding the transfer sheets 2 fed by the first sheet feeding roller 28 one by one while preventing double feeding. 29 and a separating pad 26. The bottom plate 32 of the paper feed cassette 24 is pushed up by a push-up lever (not shown) driven by a motor (not shown) until the uppermost surface of the transfer sheet 2 reaches a predetermined height.

Each of the paper feed modules 19 to 21 is divided into blocks, and not only the paper feed mechanism 4 can be configured by an arbitrary combination, but also two blocks are provided for a large number of other sheets. The block can be replaced by exchanging it with one of the above blocks. Paper feed cassette 22 of each paper feed module 19-21
24 is a front loading system which is inserted and removed from the front side of the machine body.

The transfer sheet 2 sent out from the sheet feeding mechanism 4 having the above-mentioned structure is provided with a timing roller 33 on the way.
The photoconductor 10 and the transfer charger 12 are conveyed to a transfer unit which faces the transfer unit 34 through a sheet feeding / conveying path 34. The timing roller 33 is fed with the transfer sheet 2 in a stopped state,
The skew of the transfer sheet 2 is corrected by aligning the leading ends thereof, while the timing of feeding the transfer sheet 2 to the transfer portion is adjusted depending on the timing of starting the conveyance.

FIG. 2 is a schematic view showing the drive transmission structure of the paper feed roller. Reference numeral 35 is a motor, 36 is a reverse rotation mechanism, 37 is a driving force transmission means, 38 is a detachable paper feed module, 3
Reference numeral 9 is a coupling for transmitting the driving force to the paper feed module. Each sheet feeding module is provided with an electromagnetic clutch 40 for feeding the transfer sheet at a proper timing, and the sheet feeding module is driven at a timing required.

When the transfer sheet 2 is fed, the reverse rotation mechanism 3
6 does not work, and when the feeding device is rotated in the reverse direction, the reverse rotation mechanism 3 is operated by the operation such as the gear change by the electromagnetic solenoid.
6 works. The driving force of the motor 35 is uniformly transmitted to each sheet feeding module.

Next, the feeding mechanism of the transfer sheet 2 will be described in more detail with reference to FIGS. FIG. 3 is a front view of the feeding mechanism portion of the 500-sheet storage type paper feed module 21, and FIG. 4 is a sectional view passing through the axis of the second paper feed roller. 41 is a roller shaft, 4
Reference numeral 2 denotes a support plate that supports the first paper feed roller 28, and is provided so as to be rotatable around a roller shaft 41. Second paper feed roller 2
9 is provided outside the paper feed cassette 24. 43 is a stopper that regulates the rotation of the support plate, and 44 is the roller shaft 41.
A driving boss that is rotatably engaged above, 46 is a driving boss 44
A one-way clutch provided inside the roller shaft 41 rotates idle when the roller shaft 41 rotates in the direction of arrow A (hereinafter referred to as forward rotation), and transmits the rotation to the driving boss 44 when the roller shaft 41 rotates in the reverse direction. Is attached to. 45 is a driven boss that is rotatably engaged on the roller shaft 41, and 47 is a coil spring that fits over both the driving boss 44 and the driven boss 45 with a certain tightening margin. The winding direction is such that it reverses and loosens. The support plate 42 is locked at its one end 42a so as to be integral with the driven boss 45, while the other end 42b is provided with a bearing 48.
Is rotatably engaged with. Further, another protrusion 42c of the support plate 42 contacts the stopper 43 to regulate the rotation amount of the support plate 42.

In the state before the start of the sheet feeding operation, the transfer sheet 2 is pushed up by the push-up lever so that the uppermost surface thereof has a predetermined height as described above. First paper feed roller 2
Reference numeral 8 denotes the dead weight including the support plate 42, which is pressed against the transfer sheet 2.

When the transfer sheet 2 is fed, the roller shaft 41 is rotated in the normal direction to rotate the second paper feed roller 29 in the normal direction, and the roller shaft 41 is driven as a drive source through a transmission means (not shown). The first sheet feeding roller 28, which also rotates in the same direction as the second sheet feeding roller 29, starts feeding the transfer sheet 2. Even if two or more transfer sheets are fed at this time, when the leading edge of the transfer sheet reaches between the second paper feed roller 29 and the separating pad 26, only the uppermost transfer sheet is fed by the second paper feed. The transfer sheets are fed by the rollers 29, the second and subsequent transfer sheets are prevented from moving by the separating pad 26, and only one transfer sheet is fed to the paper feed conveyance path 34 without being double fed.

After the copying operation is completed, the transfer sheet 2 blocked by the separating pad 26 remains in a state of being caught between the second sheet feeding roller 29 and the separating pad 26. Therefore, when the roller shaft 41 is rotated in the reverse direction and the second paper feeding roller 29 is rotated in the reverse direction, the transfer sheet 2 in contact with the second paper feeding roller 29 is moved.
Is sent back to the paper feed cassette 24. At the same time, the one-way clutch 46 engages with the roller shaft 41 to rotate the driving boss 44 in the same direction as the roller shaft 41. A coil spring 47 is fitted over both of the driving boss 44 and the driven boss 45 with a certain tightening allowance, and further, the winding direction is loosened when the driving boss 44 is reversed, so that the roller shaft 41 is reversed. Then, the rotational driving force is transmitted from the driving boss 44 to the driven boss 45 with a constant sliding torque. The support plate 42 that supports the first paper feed roller 28 is locked at its one end 42a so as to be integrated with the driven boss 45, while the other end 42b is rotatably engaged with the bearing 48. Therefore, when the roller shaft 41 rotates in the reverse direction, the support plate 4
2 also rotates in the same direction with a constant torque, and the first paper feed roller 2
9 is lifted and separated from the surface of the transfer sheet 2. When the protrusion 42 c provided on the support plate 42 hits the stopper 43, the coil spring 47 causes the driving boss 44 or the driven boss 4 to move.
5, the supporting plate 42 remains held at that position, only the roller shaft 41 rotates, and the operation of feeding the transfer sheet 2 back is continued.

As described above, since the second sheet feeding roller is provided outside the sheet feeding cassette, the transfer sheet is returned from the second sheet feeding roller when the fed back transfer sheet is returned into the sheet feeding cassette. Leave. On the other hand, since the first paper feed roller is separated from the upper surface of the transfer sheet, the transfer sheet is not excessively fed back, and wrinkles and paper jams do not occur.

FIG. 5 shows a sheet feeding module 1 for storing 250 sheets.
9 is a front view showing the feeding mechanism 9 and 49 is a pickup roller shaft. The mechanism for pushing up the bottom plate 30 of the cassette is different from that of the 500-sheet storage type paper feed module, and thus the feeding mechanism is also different. The shaft hole of the pickup roller 27 is formed in a substantially D shape, while the pickup roller shaft 49 has a fan-shaped cross section that fits in the shaft hole and has a play angle θ in the rotation direction.

When the transfer sheet 2 is fed, the pickup roller shaft 49 rotates in the direction of arrow B (normal rotation), and the fan-shaped one end surface 49a serves as a drive transmission surface to drive the pickup roller 27 to drive the transfer sheet. 2 is sent out, the transfer pad 25 prevents the transfer of the second and subsequent transfer sheets to prevent double feeding, and only the uppermost transfer sheet is sent out to the paper feed conveyance path 34.

When the transfer sheet 2 is fed by the pickup roller 27 and then conveyed by a conveying roller such as a timing roller 33, the pickup roller 27
Is brought into a rotating state by the movement of the transfer sheet 2. At this time, a load is applied by a friction pad (not shown) so that the play angle θ does not decrease.

After the copying operation is completed, the transfer sheet 2 blocked by the separating pad 25 remains in a state of being caught between the pickup roller 27 and the separating pad 25. Therefore, when the pickup roller shaft 49 is rotated in the reverse direction and the pickup roller 27 is rotated in the reverse direction, the remaining transfer sheet 2
Is sent back to the paper feed cassette 22. At this time, since the reverse rotation driving load is larger than the load of the friction pad, the fan-shaped other end surface 49b of the pickup roller shaft 49 serves as the reverse rotation driving transmission surface, and the transfer is performed by the distance corresponding to the rotation angle of the play angle θ. The amount of sheet return can be reduced.
As described above, this is effective in controlling the return amount of the transfer sheet when the sheet feeding mechanism 4 is configured by arbitrarily combining various sheet feeding modules in the same copying machine. That is, when paper feed modules having different numbers of sheets to be stored are mixed, the feeding mechanism is different, and the optimum return amount of the transfer sheet is different, the paper feeding drive mechanism of the copying machine main body is uniformly rotated in reverse, and each paper feeding module is operated. Therefore, it is possible to realize the optimum return amount.

FIG. 6 shows another embodiment. 6 (a) is 2
Exploded perspective view of the main part of the electromagnetic clutch provided in the 50-sheet storage type paper feed module, FIG. 6 (b) shows the operating state during forward rotation, and FIG. 6 (c) shows the operating state during reverse rotation. It is a figure. A clutch rotor 50 is provided with a boss 51 and a pin 52. Reference numeral 53 denotes an input gear, which is driven by a drive source (not shown) and is provided with an arc-shaped elongated hole 54 that is fitted to the boss 51 and engages with the pin 52.

The spring 55 is engaged with the input gear 53 and the spring stopper 56, and is provided so that the projection 56a of the spring stopper 56 and the recess 51a of the boss 51 engage with each other. The paper feed roller is biased in the forward direction (arrow C direction). The biasing force of the spring 55 is set to be smaller than the load torque of the paper feed roller.

The rotation of the clutch rotor 50 is transmitted to the output shaft 58 via the connecting / disconnecting portion 57 of the electromagnetic clutch. That is,
When the electromagnetic clutch is ON, the rotation of the clutch rotor is transmitted to the output shaft, but when the electromagnetic clutch is OFF, even if the input gear 53 rotates, the clutch rotor idles and the driving force is not transmitted to the output shaft.

When the paper feed roller rotates in the normal direction, that is, when the input gear 53 rotates in the direction of arrow C in FIG.
3 is previously urged by the spring 55 in the direction of normal rotation of the paper feed roller (direction of arrow C in FIG. 6B), and the rear end 54a of the elongated hole 54 and the pin 52 are in contact with each other. Therefore, the input gear 5
3 and the clutch rotor 52 transmit the driving force without rotation delay.

When the paper feed roller rotates in the reverse direction (direction of arrow D in FIG. 6B), when the electromagnetic clutch is OFF, the spring 5
Due to the urging of No. 5, the input gear 53 and the clutch rotor 50 run idly in the state of FIG. 6B. That is, the rear end 54a of the elongated hole 54 and the pin 52 are rotated while rotating in the direction of the arrow D, but the output shaft is not rotated. When the electromagnetic clutch is turned on, the load torque of the paper feed roller is applied to the clutch rotor, so that the front end 54b of the slot 54 of the input gear 53 contacts the pin 52, that is, the length of the slot 54 in the direction of arrow D. After idling, the state shown in FIG. After that, the pin 52 is continuously pushed by the rotation of the input gear, and the reverse driving force is transmitted to the output shaft.

In the case of this embodiment, the pickup roller and the pickup roller shaft are locked without providing the play angle θ shown in FIG. Then, the feed back amount of the transfer sheet can be controlled by the ON time of the electromagnetic clutch and the length of the elongated hole 54 of the input gear 53.

[0036]

As described above, according to the present invention, by reversing the second paper feed roller in contact with the double feed preventing means,
The first sheet feeding roller located upstream in the sheet feeding direction can be separated from the surface of the stacked transfer sheets, and the transfer sheet caught in the double-feeding prevention portion is obstructed by the first sheet feeding roller. It can be sent back into the paper feed cassette without any need. Further, according to the present invention, the paper feeding drive system is uniformly rotated in the normal direction.
Even in the case of a paper feed mechanism that is reversed and has a combination of various paper feed modules, the transfer sheet return amount can be set to an optimum value, and wrinkles and paper jams in the paper feed cassette can be prevented. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a copying machine having a paper feeding device of the present invention.

FIG. 2 is a schematic diagram showing a drive transmission structure of a paper feed roller of the present invention.

FIG. 3 is a front view of a feeding mechanism portion of the 500-sheet storage type sheet feeding module 22 of the present invention.

FIG. 4 is a cross-sectional view through the shaft of the second paper feed roller of the present invention.

FIG. 5 is a sheet-feeding module 19 for storing 250 sheets of the present invention.
Front view of the feeding mechanism

FIG. 6A is an exploded perspective view of a main part of an electromagnetic clutch provided in a 250-sheet storage type sheet feeding module of the present invention, and FIG. 6B is an explanatory diagram showing an operating state during normal rotation of the present invention. (C) is an explanatory view showing an operation state during reverse rotation of the present invention

[Explanation of symbols]

 25, 26 Separation Pad 27 Pickup Roller 28 First Paper Feed Roller 29 Second Paper Feed Roller 42 Support Plate 46 One Way Clutch 47 Coil Spring

(72) Inventor Keiichi Yoshida 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Takanori Kawaguchi, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A first feeding means for feeding a sheet in a detachable paper feed cassette to which the sheet is pressed, and a second feeding means downstream of the first feeding means. A double feed preventing unit that presses against the feeding surface of the second feeding unit;
In a sheet feeding device having means for temporarily reversing the second feeding means, when the first and second feeding means are reversed, the first feeding means is separated from the sheet. Paper feeding device characterized by. 2. A reverse rotation torque of the second feeding means is transmitted to a support member of the first feeding means via a one-way clutch and a torque limiter to separate the first feeding means from the sheet. The paper feeding device according to claim 1, wherein 3. A feeding means for pressing a sheet in a detachable paper feed cassette to feed the sheet, a double feeding preventing means for pressure-contacting a feeding surface of the feeding means, and a feeding means temporarily. A sheet feeding device provided with a means for reversing, wherein a delay mechanism is provided in the feeding means when the reversing means is operated to reverse the feeding means. 4. The feeding means comprises a paper feed roller and a roller shaft for driving the paper feed roller, and two drive transmissions of forward rotation and reverse rotation are provided at a portion where the paper feed roller and the roller shaft are engaged with each other. The sheet feeding device according to claim 3, wherein a surface is formed, and a play angle is provided between the two drive transmission surfaces to form a delay mechanism. 5. The sheet feeding device according to claim 3, wherein an electromagnetic clutch for driving and controlling the feeding means is provided, and a delay mechanism is provided between an input portion and an output portion of the electromagnetic clutch.